Auxiliary agent for the production of cellulose fibers

ABSTRACT

Methods of preparing cellulose materials, which methods comprise (a) reacting a cellulosic material with a first basic component to form alkli cellulose; (b) reacting the alkali cellulose with carbon disulfide and a second basic component to form a cellulose xanthate solution; and (c) extruding the cellulose xanthate into an aqueous coagulation bath; wherein a reaction product of an epoxide of the general formula (I):                    
     wherein R 1  represents a linear or branched aliphatic alkyl group having from about 1 to about 22 carbon atoms, and an amine compound of the general formula (II):                    
     wherein R 2  and R 3  each independently represent a substituent selected from the group consisting of —C n H 2n —O) m —H, alkyl groups having from about 1 to about 22 carbon atoms, and hydrogen, wherein n represents 2 or 3 and m represents a number of from about 1 to about 20; is present in at least one of the cellulose xanthate solution and the aqueous coagulation bath, are described. Cellulose xanthate solutions and aqueous coagulation baths containing such reaction products are also described.

BACKGROUND OF THE INVENTION

The present invention relates to the use of end group capped alkoxylatedamines as auxiliary agent in the production of cellulose fibersaccording to the viscose method and to a method for producing cellulosefibers according to the viscose method.

The viscose method is the predominant method for producing cellulosefibers on an industrial scale. It comprises converting pulp intocellulose xanthate, known as viscose, and extruding it into an acidiccoagulation bath. Contact with the acidic solution coagulates thexanthate and saponification releases the cellulose in the form of afilament.

It has been determined that the addition of auxiliary agents, known asmodifiers, to the viscose or to the spinning solution can significantlyimprove the mechanical quality of the fibers spun. The modifiers retardthe xanthate decomposition and thereby make possible the formation of auniform fiber structure (cf. Z.A. Rogowin, Chemiefasern, Georg ThiemeVerlag, Stuttgart, 1982, pages 123 ff).

Various classes of substances are known for use as modifiers, forexample quaternary ammonium bases, N-substituted dithiocarboxylic acids,polyethylene glycols and also aliphatic monoamines and especiallyethoxylated amines and amides or derivatives thereof. DE 28 37 766, forexample, describes alkoxylation products of a polyhydric alcohol and/orof a dibasic amine as modifiers. DE 29 21 314 describes a method forproducing crimped cellulose fibers using modifiers including, interalia, ethoxylated fatty acid amines of 8 to 20 carbon atoms.Furthermore, alkylamine glycol ethers are frequently used as modifiersin viscose production. These compounds are prepared by reactingalkoxylated amines with alkyl halides, preferably alkyl chlorides, inthe manner of Williamson's ether synthesis. But this method inevitablyreleases appreciable amounts of salts, the disposal of which is costlyand creates environmental problems. In some instances, moreover,residues of the alkyl chlorides remain in the reaction product and mayhave to be removed in an inconvenient and costly purification.

There is therefore a need for modifying agents which have similar orbetter properties than the prior art compounds and which can be preparedaccording to simple and less environmentally adverse methods. Moreparticularly, it should be possible to dispense with the use of chlorinechemicals entirely.

BRIEF SUMMARY OF THE INVENTION

It has been found that certain end group capped nonionic surfactantsbased on alkoxylated amines have the abovementioned properties.

The present invention includes the use of end group capped alkoxylatedamines as auxiliary agents (i.e., modifiers) in the production ofcellulose materials (e.g., fibers and sheets), particularly according tothe viscose method. The present invention includes cellulose xanthatesolutions and coagulation baths used in accordance with such processescontaining such auxiliary agents.

The present invention provides in a first embodiment for the use ofreaction products of the nucleophilic ring opening of epoxides of theformula (I)

where R¹ is linear or branched aliphatic alkyl of 1 to 22 carbon atoms,with compounds of the formula (II)

where R² and R³ are independently (C_(n)H_(2n)—O)_(m)—H or linear orbranched saturated or unsaturated alkyl of 1 to 22 carbon atoms orhydrogen, n is 2 or 3 and m is between 1 and 20, as auxiliary agent forthe production of cellulose fibers by the viscose method.

DETAILED DESCRIPTION OF THE INVENTION

The ring opening products are known compounds which can be synthesizedaccording to the customary methods of organic chemistry. The synthesisof such compounds generally takes the form of reacting the epoxides ofthe formula (I) with compounds of the formula (II) in the presence ofsuitable, preferably alkaline, catalysts, e.g., potassium hydroxide orlithium hydroxide. The use of potassium hydroxide is preferred. Anucleophilic attack of the oxygen atom of the compounds of the formula(II) on one of the epoxide carbon atoms opens the ring to form anα-hydroxy ether. Details relating to this reaction are found for examplein the paper by W. Stein in Fette, Seifen, Anstrichmittel, No. 2, volume84, 1992, page 51 and the references cited therein.

The ring opening reaction is preferably carried out under anhydrousconditions at atmospheric pressure. Depending on the type of reactantsused, the reaction temperatures required are between 100 and 180° C. Itis preferable in this connection for the reaction to be carried out inthe temperature range from 140 to 160° C.

The epoxides of the formula (I) are known compounds which are preparedby epoxidation of alpha-olefins, which are obtained by the Shop process,for example. Typical examples are the epoxides of 1-octene, 1-decene,1-dodecene, 1-tetradecene, 1-octadecene and 9-octadecene. Preference isgiven to epoxides of the formula (I) where R¹ is linear aliphatic alkylof 8 to 14 carbon atoms.

The compounds of the formula (II) are known as well. They areethanolamines or propanolamines and alkoxylation products thereof. Thesemay be obtained for example by alkoxylating mono-, di- ortrialkanolamines according to customary methods. Useful alkoxides areethylene oxide (EO) or propylene oxide (PO) or mixtures thereof.Preference is given to those compounds of the formula (II) where m isbetween 10 and 20, preferably 12 to 18. Particular preference is givento those compounds which contain ethylene oxide groups only. Preferenceis given to using those ring opening products which are prepared usingethoxylated or unethoxylated trialkanolamines, preferablytriethanolamine. Further suitable compounds are obtainable byalkoxylating other alkanolamines, eg 2-(dibutylamino)ethanol,2-(diethylamino)ethanol, 2-(methylamino)ethanol, 2-ethylaminoethanol,2-dimethylaminoethanol, ethanolamine or diethanolamine.

The molar ratio between the epoxide (I) and the compound of the formula(II) in the ring opening reaction is preferably between 1:2 and 1:1. Thering opening products typically have hydroxide numbers of at least 160,preferably of at least 180.

The ring opening products are prepared without addition of chlorinechemicals. Nor does the ring opening reaction, unlike Williamson's ethersynthesis, say, by-produce a salt.

The products obtained by ring opening may be added as modifiers not onlyto the viscose solution but also to the acidic coagulation bath intowhich the viscose is extruded. The ring opening products are preferablyadded in amounts between 1 and 5% by weight, based on the cellulose inthe viscose or in the coagulation bath.

The use of the ring opening products as modifiers in the viscosesolution facilitates the spinning process and is also observed to leadto reduced cloggage of the spinnerets. The use of the ring openingproducts as modifiers in the acidic coagulation bath is observed toproduce a more uniform decomposition of the xanthate cellulose and toretard the fiber formation process. This leads to stronger fiber. At thesame time, the precipitation of inorganic salts is prevented.

The modifiers of the invention are useful in all conventional processesfor producing cellulose fibers according to the viscose method.

From a further aspect, the present invention provides a method forproducing cellulose fibers according to the viscose method, comprisingthe steps of

a) forming alkali cellulose by reacting pulp with alkali metal hydroxidesolution

b) reacting the alkali cellulose with carbon disulfide and a lye to forma xanthate solution and

c) spinning the xanthate solution through spinnerets into an aqueouscoagulation bath containing a protic acid and metal salts to decomposethe xanthate and form a cellulose threadline,

wherein the above-described reaction products are added to the xanthatesolution and/or the coagulation bath in effective amounts as modifiers.

As used herein, viscose method refers to the industrially employedcellulose fiber production process as described for example in Z.A.Rogowin, Chemiefasern, Georg Thieme Verlag, Stuttgart, 1982, pages 67 to152.

In the practice of the method according to the invention, step a)comprises reacting cellulose, for example in the form of pressed sheets,roll material, flakes or expressed undried pulp, with a lye, initiallyto form alkali cellulose in known manner. The lyes used may be anydesired basic systems, especially aqueous alkali metal hydroxidesolutions, such as potassium hydroxide solution or sodium hydroxidesolution. The concentration is customarily 15 to 30% by weight of base,based on the total weight of the lye.

Squeezing off the excess lye leaves the alkali cellulose. There followsstep b), which comprises the individual steps of steeping, xanthationwith carbon disulfide, dissolving the xanthate in alkali metal hydroxidesolution, ripening and venting and leads to the spinnable viscosesolution. Details of this process are described for example in theabovementioned publication by Z.A. Rogowin, pages 97 to 119.

In the method of the invention, the above-described modifiers are addedto the xanthate solution during the dissolving of the cellulose xanthatein alkali metal hydroxide solution and/or during the ripening. Theamount of modifier is preferably between 1 and 5% by weight, based onthe cellulose in the solution.

The ripened xanthate solution is spun in step c) by extruding thesolution, after prior filtration and heat-treatment, through a spinnerethaving essentially round jet holes into the coagulation bath. Examplesthereof are spinnerets having 250 to 30,000 holes and a hole individualdiameter of 35 to 100 μm. In the coagulation bath the xanthatecoagulates to form fiber and is hydrolyzed by a protic acid to formregenerated cellulose, salt and carbon disulfide. The carbon disulfideis recycled back into the process. Useful protic acids are organic acidssuch as acetic acid or mineral acids such as hydrochloric, nitric orsulfuric acid. Preference is given to using concentrated sulfuric acid.The coagulation bath, in addition to the acid, also contains certainmetal salts capable of retarding the xanthate coagulation. Examples ofsuch salts are magnesium, aluminum, iron and especially zinc salts. Thesalts are customarily used as chlorides, nitrates or sulfates. Theconcentration of the salts is generally between 2 to 10 g/l.

In the method of the invention, the coagulation bath has added to it theabove-described modifiers, preferably in amounts of 1 to 5% by weight,based on the cellulose contained. The coagulation bath, in addition tothe above-described modifiers, the acid and the metal salts, may alsoinclude further auxiliary agents known to a person skilled in the art,for example formaldehyde or other modifiers. The cellulose filamentsthus obtained are then conventionally spun, purified and furthertreated.

The method of the invention is notable for modifiers of theabove-described type being used at least in one of the two steps b) orc). The method is preferably carried out in such a way that themodifiers are added only to the viscose solution prior to spinning, iein step b).

EXAMPLE

1226.7 g (1.70 mol) triethanolamine ethoxylate (17 EO) were mixed with266.6 g (1.36 mol) of α-lauryl epoxide and 12.2 g (0.065 mol) ofpotassium hydroxide in the form of a 30% by weight methanolic solutionand stirred at 160° C. for eight hours under nitrogen. The batch wasthen cooled down to 80° C. and admixed with 14.9 g (0.15 mol) of H₂O₂.After removal of water, the reaction product (1301.5 g) was obtained inthe form of a clear brownish orange liquid. Hydroxide number=182, alkalinumber =0.2, amine number =56, Lovibond color value (5^(¼) inch): 5 red,30 yellow.

What is claimed is:
 1. A mixture comprising a cellulose xanthate and areaction product of an epoxide of the general formula (I):

wherein R¹ represents a linear or branched aliphatic alkyl group havingfrom about 1 to about 22 carbon atoms, and an amine compound of thegeneral formula (II):

wherein R² and R³ each independently represent a substituent selectedfrom the group consisting of —(C_(n)H_(2n)—O)_(m)—H, alkyl groups havingfrom about 1 to about 22 carbon atoms, and hydrogen, wherein nrepresents 2 or 3 and m represents a number of from about 1 to about 20.2. The mixture according to claim, 1, wherein the reaction product ispresent in an amount of from about 1 to about 5% by weight, based on theamount of cellulose present.
 3. The mixture according to claim 1,wherein the cellulose xanthate and the reaction product are present inan aqueous alkali metal hydroxide solution.
 4. The mixture according toclaim 1, wherein R² and R³ each represent —(C_(n)H_(2n)—O)_(m)—H.
 5. Themixture according to claim 1, wherein n equals
 2. 6. The mixtureaccording to claim 4, wherein n equals
 2. 7. The mixture according toclaim 1, wherein R₁ represents a linear alkyl group having from about 8to about 14 carbon atoms.
 8. The mixture according to claim 1, wherein mrepresents a number of from about 12 to about
 18. 9. The mixtureaccording to claim 1, wherein the reaction product has a hydroxide valueof at least about
 160. 10. An aqueous coagulation bath comprising water,a protic acid and a reaction product of an epoxide of the generalformula (I):

wherein R¹ represents a linear or branched aliphatic alkyl group havingfrom about 1 to about 22 carbon atoms, and an amine compound of thegeneral formula (II):

wherein R² and R³ each independently represent a substituent selectedfrom the group consisting of —(C_(n)H_(2n)—O)_(m)—H, alkyl groups havingfrom about 1 to about 22 carbon atoms, and hydrogen, wherein nrepresents 2 or 3 and m represents a number of from about 1 to about 20.11. The coagulation bath according to claim 10, further comprising acellulose xanthate, wherein the reaction product is present in an amountof from about 1 to about 5% by weight, based on the amount of cellulosepresent.
 12. The coagulation bath according to claim 10, wherein R² andR³ each represent —(C_(n)H_(2n)—O)_(m)—H.
 13. The coagulation bathaccording to claim 10, wherein n equals
 2. 14. The coagulation bathaccording to claim 12, wherein n equals
 2. 15. The coagulation bathaccording to claim 10, wherein R¹ represents a linear alkyl group havingfrom about 8 to about 14 carbon atoms.
 16. The coagulation bathaccording to claim 10, wherein m represents a number of from about 12 toabout
 18. 17. The coagulation bath according to claim 10, wherein thereaction product has a hydroxide value of at least about
 160. 18. Amethod of preparing a cellulose material, said method comprising: (a)reacting a cellulosic material with a first basic component to formalkali cellulose; (b) reacting the alkali cellulose with carbondisulfide and a second basic component to form a cellulose xanthatesolution; and (c) extruding the cellulose xanthate into an aqueouscoagulation bath; wherein a reaction product of an epoxide of thegeneral formula (I):

wherein R¹ represents a linear or branched aliphatic alkyl group havingfrom about 1 to about 22 carbon atoms, and an amine compound of thegeneral formula (II):

wherein R² and R³ each independently represent a substituent selectedfrom the group consisting of —(C_(n)H_(2n)—O)_(m)—H, alkyl groups havingfrom 1 to about 22 carbon atoms, and hydrogen, wherein n represents 2 or3 and m represents a number of from about 1 to about 20, is present inat least one of the cellulose xanthate solution and the aqueouscoagulation bath.
 19. The method according to claim 18, wherein thereaction product is added to the cellulose xanthate solution prior toextruding the cellulose xanthate solution.
 20. A method of reducingclogging of extrusion pathways during the formation of cellulosematerials, said method comprising combining a cellulose xanthatesolution with a reaction product of an epoxide of the general formula(I):

wherein R¹ represents a linear or branched aliphatic alkyl group havingfrom about 1 to about 22 carbon atoms, and an amine compound of thegeneral formula (II):

wherein R² and R³ each independently represent a substituent selectedfrom the group consisting of —(C_(n)H_(2n)—O)_(m)—H, alkyl groups havingfrom about 1 to about 22 carbon atoms, and hydrogen, wherein nrepresents 2 or 3 and m represents a number of from about 1 to about 20;prior to extruding the cellulose xanthate solution into a coagulationbath.